Basic vs. TED

[dlloyd]

I have a multinational client that has decided to go with the ISO GTOL standards. As usual, it is the simplest things that create the most discussion. What do you call a Theoretically Exact Dimension? "Theoretically Exact Dimension" is too much of a mouthful. You could call it a "TED" (TeeEeeDee), or a Ted (short for Teddy or Theodore). I keep inadvertently referring to them as "basic" because that is what I have been doing for 40 years. I am told that in a lot of countries "basic" translates to "nominal".

Are there others out there that are using the ISO standards, and if so what term do you use for Theoretically Exact Dimension?

I would also be interested in how you handled the transition from envelope requirement to independency principle, if you did.

[Kelly_Bramble]

Welcome to Engineers Edge!

Well yes, I mix up “TED” and “Basic Dimension” in conversation all the time. You just got to try to think before you speak . Also, I think it is fair that the listener should appreciate and understand what you really mean. There are more important things to discuss in meetings other than terminology precision.

ISO standards are used pretty much most places outside of the USA. Many countries have created a derivative standard of ISO1101 via their regions standards organization.

As far as the default difference between ASME and ISO on the “Envelope Principal (Rule #1)” And “Principal of Independency” – I happen to like ISO default better (another discussion).

Some folks want to invoke the Envelope Requirement on all features, so they include a note on the engineering drawing indicating that the “Envelope Requirement applies to all Features of Size”. Other organizations just use the circle “E” placed next to dimensions/tolerances where it is desired to control to the Envelope Requirement.

[PinkertonD]

DL, are you building a wood fired pizza oven???

[dlloyd]

I assume in normal conversation you don't refer to them a "theoretically exact dimensions". Do you refer to them as "TEDs" as in the man's name short for Theodore or as "TeeEeeDees"? I want to try to get everyone on the same page.

[PinkertonD]

DL, do you work for our Government? I have been in meetings like this.

During my one and only brief foray into Government Engineering departments, I recall once where a meeting was called to discuss when to have the next meeting. Bbbbrrrr, things that wake me up with the sweats in the night.

Is internal nomenclature that you are worried about? What does it matter what you call them. Call them Red-Eggs. As long as everyone stays on the same page, they will always be Red-Eggs or "RE"

[Kelly_Bramble]

I assume in normal conversation you don't refer to them a "theoretically exact dimensions". Do you refer to them as "TEDs" as in the man's name short for Theodore or as "TeeEeeDees"? I want to try to get everyone on the same page.

Well, I think if one wants to say "theoretically exact dimensions" - it's not wrong. For me, I would simply get an agreement that "Basic Dimension" = "Theoretically Exact Dimensions" or "TED".

Also, referring to a "Nominal" dimension as a "Basic" dimension is tribal slang and not embraced by ISO1101 (E) - 2004.

Most correctly the ISO folks should say "Nominal" feature or "Ideal" feature. Further drill down one might use "Integral Feature" or "Derived Feature". See ISO 1101(e) - 2004 page VI as well as page 8.

As an older guy with other thirty years engineering experience, I would recommend one learn to recognize “different” as opposed to “wrong” when in meetings. If clarification is needed – ask and move on.

[dlloyd]

PinkertonD, I realize we can internally call them Red-Eggs if we choose to, but we are not an island. We have many vendors and sub-contractors throughout the world. Will they know what Red-Eggs are? I prefer to conform to some kind of a norm so we don't have to get everyone who is involved with supplying parts to us conform to our unique terminology. Isn't that, afterall, what standardization is about?

I am simply asking, to those who are using the ISO GTOL standards, do you refer to them in normal conversation as "theoretically exact dimentsion", "Teds" (as in the man's name), "T.E.D.s", "basic" or "Red-Eggs"? That way, when we communicate with those around the world, whom we have never met face-to-face, and whose first language is not ours, the communications will be better than it could be. We in the US are probably going to have to change our terminology. I don't want to ask others throughout the world to change their terminology if I don't have to. I am simply asking what term do those using ISO use? That is all. We have not had a meeting about this as most in the meeting would not have a clue. But how would that be different than most meetings?

[dlloyd]

Kelly, since we are dealing with a global economy, even if "basic" is tribal slang, I want to avoid using it with a different meaning. Communications with those whose first language is other than mine is difficult enough without intentionally trying to change the meaning of even their slang if you can avoid it. We can avoid it if we use the correct terms. Right now I am leaning toward "TeeEeeDee" unless I find that something else is common in the universe.

[Kelly_Bramble]

Kelly, since we are dealing with a global economy, even if "basic" is tribal slang, I want to avoid using it with a different meaning. Communications with those whose first language is other than mine is difficult enough without intentionally trying to change the meaning of even their slang if you can avoid it. We can avoid it if we use the correct terms. Right now I am leaning toward "TeeEeeDee" unless I find that something else is common in the universe.

Yes, consistency in terminology is for simplicity, however in my seven times + around the world consulting and training dimensioning and tolerancing to ISO, ASME an ANSI standards I have never heard "TeeEeeDee" or spoken it.

I recommend simply "TED", like the name.

[Kelly_Bramble]

Yes, consistency in terminology is for simplicity, however in my seven times + around the world consulting and training dimensioning and tolerancing to ISO, ASME an ANSI standards I have never heard "TeeEeeDee" or spoken it.

I recommend simply "TED", like the name.

Ok, just thinking about this I'm going to retract my statement as I have heard "TeeEeeDee" spoken at a customer in South Africa, India and recently up in Detroit.

For me either "TED" the name or "TeeEeeDee" works just fine.

You said

We in the US are probably going to have to change our terminology.

The term "Basic" has been around a long time, definitely before the 1966 ANSI standard was published. Why does the US need to change?

[Belanger]

Since you're just asking about what to say in conversation, why not just say "boxed dimensions"? That way, everyone knows what you're talking about, and you don't slight anyone who is partial to ASME or ISO.

I know it's not a term used in the standards, but you just asked what to call them for ease. It gets the point across...

[dlloyd]

Kelly, if we were to invoke the Envelope Requirement by a note or invoking ISO 2768...-E, how would you invoke the Independency Principle (in the rare event you wanted to) since the I in a circle symbol is not recognized by ISO?

[dlloyd]

Kelly, let me clarify. We in the US are probably going to have to change our terminolgy if we are going to adopt any standard that uses a different term than we are accustomed to. My goal would be a global standard, and I expect we are all going to have to change somewhat if we are ever going to accomplish that.

[dlloyd]

For me, I would simply get an agreement that "Basic Dimension" = "Theoretically Exact Dimensions" or "TED".

Get agreement with whom. I am trying to implement something that will be used by our company worldwide, and I don't know who the players and suppliers are today, much less in the future. Again, just wanting to know what do the majority of folks who are currently using ISO GTOL use in referring to TEDs.

As an older guy with other thirty years engineering experience, I would recommend one learn to recognize “different” as opposed to “wrong” when in meetings. If clarification is needed – ask and move on.

As an even older guy with 40+ years engineering experience (I have retired twice) I certainly recognize different and wrong. I must not be making myself clear. I (we) have no problem with any term. It is just no clear to me what the common term is for a "theoretically exact dimension" in the ISO using community - is it TED, Ted or ????

[Kelly_Bramble]

Kelly, if we were to invoke the Envelope Requirement by a note or invoking ISO 2768...-E, how would you invoke the Independency Principle (in the rare event you wanted to) since the I in a circle symbol is not recognized by ISO?

In ISO, the principle of independency is default for features of size except those associated with position, coaxiality or datum reference with a material modifier (MMR or LMR).

With the above requirement understood, I would create note saying something to the effect that the envelope requirement applies to all features of size unless otherwise noted.

For those features in the “otherwise noted” category I would create a delta (flag) note saying that the “Envelope Requirement DOES NOT apply to indicated features.” BTW, one does not put a “Circle” E within a note. Don't forget to associate the delta (flag) note with the feature needing envelope control...

[Belanger]

Kelly -- it's actually pretty common to use the circled E within a general note. Are you saying that ISO prohibits that, and actually requires the note to use the word "envelope"?
Also, for a print where the envelope principle is invoked by a general note, I think you meant to say that a local flag note would not require the envelope for the indicated features. The local note you suggest simply repeats what the general note would be saying

[Kelly_Bramble]

Kelly -- it's actually pretty common to use the circled E within a general note. Are you saying that ISO prohibits that, and actually requires the note to use the word "envelope"?

John-Paul, well I just looked at the ISO standard and it does NOT explicitly say one cannot use the literal “Circle E” within a note or otherwise. So, until noted otherwise in the standard one seems to be able to use the actual geometrical symbology in notes, unlike the ASME and older ANSI standards. – I stand corrected in other words…

Also, for a print where the envelope principle is invoked by a general note, I think you meant to say that a local flag note would not require the envelope for the indicated features. The local note you suggest simply repeats what the general note would be saying

Yes John-Paul – I edited my post and corrected it – Thanks!

[Kelly_Bramble]

Kelly, if we were to invoke the Envelope Requirement by a note or invoking ISO 2768...-E, how would you invoke the Independency Principle (in the rare event you wanted to) since the I in a circle symbol is not recognized by ISO?

Just looking at ISO 2768 – E revision titled:
General Tolerances –
Part 1: Tolerances for linear and angular dimensions without individual tolerance indications.

There isn’t any statement or otherwise in this standard that invokes the envelope requirement for features of size on an ISO 1101 drawing.